Coma vs. Brain death

  • coma = not awake and not aware
    • but, could still have spinal and brainstem reflexes preserved but still in coma
  • brain dead is death by neurologic criteria
  • time course for chronic phase/using “vegetative state” term
    • persistent vegetative state = 1 mo timecourse
    • 3 mo for non-trauma; 12 mo for trauma

Spectrum of cognitive and motor fxn

  • Bernat et al Annu Rev Med 2009 -> what is death/consciousness
  • spectrum -> conscious state vs. motor fxn
    • purposeful interaction with the world
    • vegetative state (APPLICABLE TO CHRONIC STATES/not ICU pts)
    • coma

Covert / functional locked in syndrome

  • adaptive tech is able to pick up their yes/no paradigms despite looking like they’re completely locked-in
  • they have awareness of the world around them
  • fMRI for example could be the adaptive tech that shows you’re able to interact w/ the world

Death (multiple different definitions)

  • legal
  • ethical
  • medical
  • biophysical -> cessation of critical fxn of the organism as a whole

Ventilator and ECMO has changed the way we view death

  • b/c can have devastating neuro injury but pt is still alive via vent; so concept of brain death didn’t come up until 1950s/when vents were invented

Brain death <- remember full brain death differs from usual death exam (central/peripheral pulse, lack of respirations)

  • functional imaging is changing the paradigm
  • binary definition; never “brain dead, except…”
  • should have a local policy at specific hospital you work at
    • variation in the types of exam and the time course between exams
  • not emergent; but, it is urgent
  • not optional to do the brain death test
    • CA law may have part where family can object? but, usually it is not optional.
  • “whole brain” vs. “brainstem” death
    • no universal definition unfortunately in society
    • whole = demonstrate that entire brain is NOT fxn’ing
    • brainstem = demonstrate that brainstem is out and not coming out -> brainstem could be out (i.e. brainstem stroke) with EEG activity on the cortex
    • in the US you have to investigate the other areas of the brain -> if they have massive pontine and cerebellar hemorrhage, you still need to do EEG to interrogate the cortex (i.e. the rest of the brain)
  • interestingly, as clearly not ALL the cells are dead
  • can say to families “irreversible brain damage” or your family has “brain damage”
    • AVOID term of BRAINDEAD unless you’re absolutely sure

Strict criteria

  • complete cessation of neuro fxn
  • cerebral circ arrest
  • testing for brain death is not optional, but in CA, the family can refuse
  • generally, a clinical diagnosis -> though ancillary testing can be performed ONLY if unable to declare clinically

Obstacles to brain death exam

  • lytes
  • e.g. of cannot perform brain death exam: cannot tolerate the apnea test (i.e. Hirsch’s first pt as attending, she put a CVICU pt on T-piece and the pt coded); cervical cord injury (you don’t know if that circuit is intact); in trauma pt missing an eye
  • severe c spine injury or max/face injury <- precluding exam
  • temp
  • severe pCO2 acidemia

Nuclear perfusion test <- this is the test of choice at Stanford

  • glucose labeled; injected at the bedside; come back 1h later and see if cerebral uptake (if uptake, then it’s not brain death); take picture of the head at bedside with nuclear imaging device (?specifically, unclear)
  • tracer takes time to obtain
  • it’s on California Ave

EEG -> has to be done in a specific way

cerebral angiogram -> looking for cessation of flow; this is gold standard at time of this lecture for “ancillary testing”

  • inject and you see vessel fill but then should see blood flow stop
  • it’s hard practically to do this b/c have to get cath lab study

TCDs <- unreliable; we don’t really use them

evoked potentials (peripheral stimulation) -> not validated for brain death; used for prognostics

Brain death exam (https://www.pathlms.com/ncs-ondemand/courses/1223)

  • need a cause
  • exclude confounding factors -> tox/temp, HD, uremia, hepatic failure, facial/c spine trauma, NMB
    • this one is very important; unfortunately, this part of confounding factors is under constant debate -> e.g., how many half-lives should you wait for certain drugs on board (Stanford’s policy is 5 half-lives of a medicine; things like barbituates take a long, long time)
  • do brain death exam/cranial nerves -> by two teams 1h apart; only one may need apnea test (usually, the second test is done w/ apnea exam)
    • licensed MD with experience and comfort doing the brain death exam
    • the other exam must be done by the neurology or NSGY attending

Steps to Hirch’s brain death exam (temp > 36C and SBP > 100 mmHg)

  • MAR/med review
  • normothermia (core should be > 36C); adequate BP (SBP > 100 mmHg)
  • document cause
  • document that not triggering vent -> turn down/off the backup rate and that pt not overbreathing the vent (do if you’re not worried that they’re not dangerously hypoxic)
  • document there’s no HR or BP change w/ pain
  • document no motor response w/ central/peripheral pain
  • peripheral pain; central pain
    • No response (other than spinal cord response) to painful stimuli in all 4 limbs
  • cranial nerves:
    • pupils via pupillometer
    • cold calorics in one ear; then wait 5 min until the next ear (use small angiocath) <- don’t worry about COWS mnemonic; just make sure eyes don’t move
    • corneal reflexes absent
    • oculocephalics/doll’s eyes
    • no cough/gag on deep suctioning
    • no grimace to supraorbital nerve or TMJ
  • apnea test
    • Normal PCO2 -> Then, disconnect the vent
    • Should have absent spontaneous respirations for time long enough for PCO2 to get 60 mmHg or 20 mmHg from baseline
    • *on ECMO, turn down sweep and turn down the ventilator; can run oxygen down the tube just to avoid dangerous hypoxia; usually though, ECMO pts get ancillary tests too to test brain death
    • ABG at 7 min

Donation after brain death

Donation after Circulatory Death (DCD) -> end stage disease and you’re planning to withdraw care; expectation that pt will die within 1h after withdrawal

*“thank you for bringing it up; in situations ilke this, there is a separate team that will d/w you about organ donation; they are separate from our team; when you are ready, i will step out and they can talk with you”

*ethics consult should be pursued for DCD cases <- end-stage disease where you’re thinking about care withdrawal

  • usually age < 60 for DCD cases

*”it’s very kind of you to be thinking of other people during this time, we will gather the appropriate info; in the meantime i encourage you to process the info we just provided and we’ll follow up with you soon”

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